JP4345602B2 - Thermal transfer receiving sheet, method for producing the same, and image forming method using the same - Google Patents

Description

  The present invention relates to a thermal transfer receiving sheet which is superposed on a thermal transfer sheet (ink ribbon) and forms an image by thermally transferring the dye of the ink ribbon with a thermal head. More specifically, the present invention is particularly suitable for a dye thermal transfer printer, and has a thermal transfer receiving sheet (hereinafter, also simply referred to as “receiving sheet”) having an intermediate layer containing hollow particles between a sheet-like support and an image receiving layer. And a manufacturing method thereof and an image forming method using the same.

  In recent years, thermal printers have attracted attention, and dye thermal transfer printers that can print clear full-color images have attracted attention. The dye thermal transfer printer superimposes a dye layer containing a dye of an ink ribbon and an image receiving layer (hereinafter, also simply referred to as “receiving layer”) containing a dye-stainable resin of a receiving sheet, and a thermal head. The image is formed by transferring the dye at a required portion of the dye layer to the receiving layer by a predetermined concentration by heat supplied from the above. The ink ribbon sequentially has dye layer regions of three colors of yellow, magenta and cyan, or four colors obtained by adding black to this. A full-color image is obtained by repeatedly transferring each color dye on the ink ribbon to the receiving sheet in order. In such a dye thermal transfer type printer, the receiving sheet is generally supplied in a sheet state.

  The development of digital image processing technology using computers has greatly improved the image quality of recorded images and the market for dye thermal transfer systems. In addition, with the improvement of the thermal head temperature control technology, there is an increasing demand for higher speed and higher sensitivity of the printing system. Therefore, how to efficiently use the amount of heat generated by a heating device such as a thermal head for image formation is an important technical issue. In addition, there is a demand for printer price reduction and structure simplification, and lowering of the printing pressure by a thermal head and extending the life of the head are also technical issues. Currently, printers that can print one A6 size within 30 seconds are also on sale, and it is expected that there will be further demands for higher printing speeds in the future.

In general, in order to efficiently form an image with high image quality and high density, a receiving sheet provided with a receiving layer mainly composed of a dye-dyeable resin on a support is used. When a normal film is used, it has excellent smoothness, but the heat from the thermal head escapes to the base material, resulting in insufficient recording sensitivity, and the film does not have sufficient cushioning properties. Inadequate adhesion results in density unevenness.
In order to solve such problems, a support in which a foam film is bonded to a core material layer such as paper as a support (see, for example, JP-A-61-197282 (Patent Document 1)), polyolefin. There has been proposed a support or the like in which a biaxially stretched film (synthetic paper) containing a thermoplastic resin such as a resin as a main component and including a void (void) structure is bonded to a core material layer such as paper (for example, (See Kaisho 62-198497 (Patent Document 2).) Receptor sheets using these supports are excellent in heat insulation and smoothness, but have disadvantages such as no paper-like texture and high cost.

  Also, when paper is used as a support for the receiving sheet, the recording sensitivity is insufficient as in the case of the film, and the cushioning property is slightly better than that of the film, but uneven adhesion between the ink ribbon and the receiving layer due to uneven density of paper fibers. Due to this, there is a tendency that unevenness of the printed image occurs. Therefore, a receiving sheet is disclosed in which an intermediate layer containing hollow particles is provided between a paper support and a receiving layer in order to improve transfer density and the like (for example, JP-A-63-87286). (See Patent Document 3) and Japanese Patent Laid-Open No. 1-27996 (Patent Document 4). The sensitivity of this receiving sheet is improved by the effect of improving the heat insulating property and cushioning property of the hollow particle-containing layer, but there is a tendency that the receiving sheet surface is uneven due to the influence of the hollow particles.

  Regarding the improvement of the unevenness on the surface of the receiving sheet, a receiving sheet having a specific surface roughness, glossiness, etc. has been proposed by defining the average particle diameter and hollowness ratio of the hollow particles used in the intermediate layer (for example, special features (See Kaihei 9-99651 (Patent Document 5) and JP-A-2001-39043 (Patent Document 6).) In addition, in a receiving sheet formed by forming a resin layer including a bubble layer and a receiving layer on a base sheet, a method for smoothing the bubble layer and / or the receiving layer has been proposed (for example, Japanese Patent Laid-Open No. 6-210968 (Patent Document 7).)

  However, there is not necessarily a sufficient correlation between the value of the surface roughness of the receiving layer by the conventional measuring method and the image quality by the actual dye thermal transfer printer. In particular, it is difficult to obtain good image quality by printing with a printer at a high speed and a low printing pressure as at present. Moreover, when the volumetric hollow ratio of the hollow particles is increased, the surface of the receiving sheet is easily damaged. That is, when handling the printed matter, the nail, the nib and the like are liable to be scratched on the surface of the sheet, and there is a problem that the commercial value is remarkably lowered.

JP 61-197282 A (first page) JP-A-62-198497 (first page) JP-A-63-87286 (page 1-2) Japanese Patent Laid-Open No. 1-27996 (page 1-3) JP-A-9-99651 (page 1-5) JP 2001-39043 A (page 2-3) JP-A-6-210968 (page 2-4)

  The present invention has been made in view of the circumstances as described above, and solves the above-mentioned problems of conventional dye sheets, and is particularly suitable for dye thermal transfer printers, and is a receiving sheet provided with an intermediate layer containing hollow particles. In low-cost, high-sensitivity, high-quality images that have the same print density as synthetic paper and foam film without using expensive synthetic paper or foam film, and have improved unevenness in density and white defects. An object of the present invention is to provide a thermal transfer receiving sheet, a manufacturing method thereof, and an image forming method using the same.

The present invention includes the following inventions.
(1) In the method for producing a thermal transfer receiving sheet in which an intermediate layer containing hollow particles and an image receiving layer are sequentially formed on at least one surface of a sheet-like support, the average particle diameter is 0 on at least one surface of the sheet-like support. After applying the intermediate layer coating liquid containing hollow particles having a volume hollowness ratio of 75 to 95% and drying to provide the intermediate layer and / or on the intermediate layer After the image receiving layer is provided, a smoothing process is performed through a nip portion of a pair of rolls including a heating roll and a press roll, and the applied pressure is 0.1 MPa using a microtopograph on the surface of the thermal transfer receiving sheet. The print smoothness (Rp value) measured 10 ms after the start of pressurization is 1.5 μm or less, and after the smoothing treatment step, in the state of release of pressurization, the thermal transfer acceptance sheet A method for producing a thermal transfer receiving sheet, comprising a step of restoring the thickness of the heated surface in contact with a heating roll.

(2) In a thermal transfer receiving sheet in which an intermediate layer containing hollow particles and an image receiving layer are sequentially formed on at least one surface of a sheet-like support, the average particle diameter of the hollow particles is 0.5 to 10 μm and the volume is hollow The printing smoothness (Rp value) measured by using a microtopograph on the surface of the thermal transfer receiving sheet with an applied pressure of 0.1 MPa and 10 msec from the start of pressurization is 1.5 μm. An image forming method in which a pressure transfer process of 1.0 MPa or more is performed on the surface of a thermal transfer receiving sheet at the time of printing and / or after printing with a dye thermal transfer printer, using the thermal transfer receiving sheet characterized by the following.

  The receiving sheet of the present invention is suitable for a dye thermal transfer printer, has an intermediate layer containing hollow particles, has improved uneven density, white spots, etc., and can be recorded at low cost, with high sensitivity and high image quality. It is a receiving sheet with excellent quality. Furthermore, the image processing method of the present invention has made it possible to improve the occurrence of scratches and scratches on the print surface.

Next, the present invention will be described in more detail with reference to preferred embodiments.
In order to obtain high-sensitivity and high-quality images, the receiving sheet is sufficiently in close contact with the ink ribbon during printing, and further deforms following the shape of the thermal head to efficiently form heat from the thermal head. It is necessary to use it. Accordingly, the receiving sheet is required to have high smoothness on the surface of the receiving sheet under the applied pressure during printing.

  As a result of intensive investigations in the present invention, the printing smoothness of the receiving sheet surface (receiving layer surface) when measured using a microtopograph at a pressure of 0.1 MPa and 10 msec (millisecond) after the start of pressurization. It was found that a high-sensitivity and high-quality image can be obtained by setting the (Rp value) to 1.5 μm or less. The Rp value is substantially 0 to 1.5 μm, preferably 0 to 1.0 μm. When the Rp value exceeds 1.5 μm, the smoothness of the receiving sheet surface is insufficient, and the printing density and printing image quality of the receiving sheet may be inferior.

  Note that the printing smoothness (Rp value) in the present invention is a physical quantity measured in proportion to the average depth of the indentation on the sample surface pressure-bonded to the reference plane (prism). , Vol.17, No.3 (1978), Japan Printing Society 60th Spring Research Presentation (1978), etc. On the other hand, in the paper manufacturing industry, in order to generally indicate the smoothness of paper, devices that calculate smoothness from the amount of air leakage such as Beck smoothness meter, Oken type smoothness meter, or smoother smoothness meter are often used. Has been. However, when considering printing with a printer, it has been found that the printing smoothness (Rp value) under a specific condition can satisfactorily reproduce the contact state between the receiving sheet and the thermal head in the actual printing.

  When the sublimation dye is transferred from the ink ribbon to the receiving layer of the receiving sheet and an image is formed, the pressure applied to the receiving sheet by the pressing force between the thermal head of the printer and the platen roll is usually 0.1 to 0. The application time of thermal energy from the thermal head is generally 10 ms or less, and the smoothness of the receiving sheet under pressure in a very short time, that is, the contact ratio between the receiving sheet and the thermal head is important. It can be seen that it is.

  Conventionally, a specular reflection smoothness meter (also referred to as “Chapman smoothness meter”) is known as a device for measuring the optical contact ratio between a glass surface and paper under pressure. This specular reflection smoothness meter can reproduce the applied pressure in thermal transfer printing, but it takes several seconds from the start of pressurization to read the measured value of the contact rate, even if it is the fastest, the thermal energy application time in the actual thermal transfer printing It takes a very long time compared to the above, and it is far from reproducing the actual printing state.

  On the other hand, the print smoothness (Rp value) can be calculated by measuring the optical contact rate between the prism surface and the paper 10 ms after the start of pressurization at the shortest, and the Rp calculated from this contact rate. As a result of investigating the relationship between the value and the print image quality, it was found that the Rp value measured 10 msec after the pressurization of the pressure of 0.1 MPa to the prism of the receiving sheet was highly correlated with the print image quality. As the measuring device, for example, a printing smoothness tester (optical contact rate measuring device, microtopograph, manufactured by Toyo Seiki Seisakusho) can be used.

  Moreover, it is preferable that the compressive elasticity modulus measured according to JISK7220 of the receiving sheet of this invention is 30 Mpa or less, More preferably, it is 3-20 Mpa, Especially preferably, it is 4-16 Mpa. When the compressive elastic modulus of the receiving sheet exceeds 30 MPa, the image quality may be deteriorated, or ribbon wrinkles may be generated on the stamp screen, thereby reducing the commercial value.

  Since the compression elastic modulus of the receiving sheet of the present invention is a sufficiently low value, when the receiving sheet is sandwiched between the thermal head and the platen roller via the ink ribbon during printing, the inside of the receiving sheet is appropriately deformed and thermally Adhesion between the head and the receiving sheet is improved, and excellent recording density and image quality can be obtained.

  Also, the ink ribbon locally heat shrinks due to the heat of the thermal head, and wrinkles are generated. However, since the compression elastic modulus of the receiving sheet is sufficiently low, the receiving sheet may be deformed following the shape of the wrinkles. The shape of the wrinkles generated on the ink ribbon is not transferred to the printing screen and can show a good appearance. However, when the compression elastic modulus is high, the receiving sheet cannot be sufficiently deformed following the shape of the wrinkle, so that the shape of the wrinkle generated on the ink ribbon is transferred to the printing screen, resulting in poor appearance.

The layer structure of the receiving sheet of the present invention has at least a sheet-like support, an intermediate layer, and a receiving layer, and these layers will be described in detail below.
(Sheet support)
Examples of the sheet-like support of the present invention include (1) high-quality paper (acidic paper, neutral paper, etc.), medium-quality paper, coated paper, art paper, glassine paper, cast coated paper, at least one of polyolefin resin, etc. Main component of cellulose pulp such as laminated paper, synthetic resin impregnated paper, emulsion impregnated paper, synthetic rubber latex impregnated paper, synthetic resin internal paper, foamed paper containing thermally expandable particles, paperboard, etc. (2) Polyolefins such as polyethylene and polypropylene, polyesters such as polyethylene terephthalate, plastic films mainly composed of thermoplastic resins such as polyamide, polyvinyl chloride, polystyrene, etc. A molten mixture containing a soluble resin or inorganic pigment is extruded from an extruder and stretched to generate voids. Porous stretched film (for example, synthetic paper, porous polyester film) having a single layer structure or multilayer structure, or a composite of these films or a laminate of these films and other films or papers A film etc. are used suitably.

Among the above-mentioned various sheet-like supports, papers mainly composed of cellulose pulp have low heat shrinkability, good heat insulation, good texture as receiving paper, and are inexpensive. Are preferably used.
The sheet-like support of the present invention may have a structure in which a first base material layer on which a receiving layer is formed, an adhesive layer, a release agent layer, and a second base material layer may be sequentially laminated. Of course, a sheet-like support having a structure of the type can also be used.

  The sheet-like support used in the present invention preferably has a thickness of 100 to 300 μm. Incidentally, if the thickness is less than 100 μm, the mechanical strength is insufficient, the rigidity of the receiving sheet obtained therefrom is small, the repulsive force against deformation is insufficient, and the curling of the receiving sheet that occurs during printing is reduced. There are cases where it cannot be sufficiently prevented. Further, if the thickness exceeds 300 μm, the thickness of the receiving sheet obtained is excessive, so that the capacity of the printer increases when the number of receiving sheets stored in the printer is reduced or when a predetermined number of sheets is stored. May cause problems such as making it difficult to make the printer compact.

(Middle layer)
In the present invention, an intermediate layer is formed on at least one side of the sheet-like support. Since the intermediate layer has a porous structure mainly composed of a binder resin and hollow particles and has a high cushioning property, a highly sensitive receiving sheet can be obtained even when paper is used as a sheet-like support. By containing hollow particles in the intermediate layer, the receiving sheet is given a suitable degree of deformation freedom, and the followability and adhesion of the receiving sheet to the printer head shape and ink ribbon shape are improved. The thermal efficiency of the printer head can be improved, the print density can be increased, and the image quality can be improved. Further, in the high energy application operation of the high-speed printer, it is possible to prevent printing defects due to ribbon wrinkles generated on the ink ribbon at the same time.

  By including hollow particles in the intermediate layer, the heat insulating property of the receiving sheet is improved, thereby improving the thermal efficiency of the thermal head with respect to the receiving layer, thereby increasing the print density and improving the image quality. Even if the receiving sheet is subjected to high pressure by the thermal head and the conveying roll of the printer, it is possible to absorb this stress inside the receiving sheet, so that spike marks and dents on the printing screen are formed by the conveying roll of the receiving sheet. Resistance to is improved.

The hollow particles used in the intermediate layer of the present invention are composed of a shell formed of a polymer material and one or more hollow portions surrounded by the shell, and the method for producing the hollow particles is exceptional. There is no limitation, but it can be selected from those manufactured as shown in (a) and (b) below.
(A) Expanded hollow particles produced by thermally expanding a thermoplastic polymer material containing a thermally expandable substance (hereinafter sometimes referred to as “pre-expanded hollow particles”).
(B) The pore-forming material is volatilized and escaped from the microcapsules produced by the microcapsule polymerization method using the polymer-forming material as the shell-forming material and the volatile liquid as the pore-forming material. Microcapsule-like hollow particles obtained by the above process.

  Also, as hollow particles, particles (expandable particles) made of a thermoplastic material containing a thermally expansible material are used in an unfoamed state, and foamed by the heat in the manufacturing process of the receiving sheet, for example, the drying process. It is also conceivable to form foamed hollow particles. However, as described above, if a thermoplastic material containing a thermally expandable material is foamed by heating during the manufacturing process of the receiving sheet, it is difficult to foam to a uniform particle size, and the particle size after thermal expansion is strictly limited. Since it cannot be managed, the surface of the intermediate layer becomes a surface with large irregularities, and the smoothness may be inferior. Since the receiving sheet having the intermediate layer as described above also has large irregularities on the surface of the receiving layer, the uniformity of the heat-transferred image may be lowered and the image quality may be inferior. Therefore, in the present invention, pre-expanded hollow particles produced by thermally expanding particles made of a thermoplastic material containing a thermally expandable material in advance are preferably used.

  The foamed hollow particles produced by thermally expanding a thermally expandable material-containing thermoplastic material are, for example, low-volatile materials such as n-butane, i-butane, pentane, and / or neopentane as a thermally expandable core material. A boiling point hydrocarbon is encapsulated in a thermoplastic material, and a homopolymer or copolymer such as vinylidene chloride, vinyl chloride, acrylonitrile, methacrylonitrile, styrene, (meth) acrylic acid ester or the like is used as the thermoplastic material in a capsule shell ( The particles obtained as a (wall) material are subjected to a treatment such as heating in advance, so that they are thermally expanded to a predetermined particle diameter to obtain pre-expanded hollow particles.

  Further, the foamed hollow particles produced by thermally expanding the thermoplastic material-containing thermoplastic material as described above generally have a small specific gravity. Therefore, for the purpose of further improving the handling workability and dispersibility, Foamed composite hollow particles in which an inorganic powder such as calcium, talc, titanium dioxide or the like is adhered to the surface of the already foamed hollow particles by heat fusion and the surface is coated with the inorganic powder can also be used in the present invention.

  The microcapsule-like hollow particles used in the present invention contain a polymer material, for example, a styrene-acrylic copolymer or a hard resin such as a melamine resin as a shell, and a volatile liquid such as water in the core. The microcapsule is dried, and water is volatilized and escaped to form a hollow core part. This microcapsule is obtained from a polymer-forming material (shell-forming material) and a volatile liquid (pore-forming material) by a microcapsule-forming polymerization method.

  The average particle diameter of the hollow particles used in the present invention is 0.5 to 10 μm, preferably 0.8 to 8 μm. When the average particle diameter of the hollow particles is less than 0.5 μm, the volumetric hollow ratio of the obtained hollow particles is low, so that the heat insulation and cushioning properties are generally low, so that the sensitivity and the image quality improvement effect are sufficiently obtained. There may not be. On the other hand, when the average particle diameter exceeds 10 μm, the smoothness of the surface of the obtained intermediate layer is lowered, the unevenness of the surface of the receiving sheet is increased, the uniformity of the thermal transfer image is insufficient, and the image quality may be inferior.

Further, the maximum particle diameter of the hollow particles used in the present invention is preferably 25 μm or less, more preferably 20 μm or less. If the maximum particle diameter of the hollow particles exceeds 25 μm, the thermal transfer image may cause unevenness in density of prints and white spots due to coarse particles, resulting in poor image quality. In order to prevent the hollow particles from containing coarse particles having a maximum particle size exceeding 25 μm, in the production of hollow particles generally exhibiting a normal distribution state, by adjusting the set value of the average particle size. It is possible to respond. Further, by providing a particle classification step, it is possible to reliably obtain hollow particles that do not contain coarse particles.
In addition, the particle diameter of the hollow particles described in the present specification can be measured using a general particle size measuring device, and a laser diffraction type particle size distribution measuring instrument (trade name: SALD2000, manufactured by Shimadzu Corporation) is used. It is a measured value.

  The volume hollowness of the hollow particles used in the present invention is preferably 75 to 95%. When the volumetric hollow ratio is less than 75%, the image quality may be deteriorated. On the other hand, if the volume hollowness exceeds 95%, the strength of the coating layer is inferior, and the hollow particles may be destroyed during coating and drying, leading to a decrease in surface smoothness.

The volumetric hollow ratio of the hollow particles is measured using a direct chemical balance (sensitivity 1 mg), a volumetric flask (100 ml), a sieve (12 mesh) as a measuring instrument, and isopropyl alcohol (IPA) as a reagent. The hollow particles used are those previously dried at 45 ° C. for 48 hours and used as measurement samples. The true specific gravity is measured by the following procedure.
(1) Weigh accurately the volumetric flask (W1).
(2) About 0.5 g of sample is put in a volumetric flask and precisely weighed (W2: volumetric flask + sample).
(3) Add IPA to the marked line and weigh accurately (W3: volumetric flask + sample + IPA).
(4) Add IPA to the marked line as a blank and precisely weigh it (W4).
The true specific gravity and the hollow ratio are calculated by the following formulas.
True specific gravity = A / B
However, A = (W2-W1) × {(W4-W1) / 100}
B = {(W4-W1)-(W3-W2)}
Hollow ratio (%) = {1-1 / (specific gravity of membrane material / true specific gravity)} × 100

  The blending amount of the hollow particles in the intermediate layer is preferably in the range of 30 to 75% and more preferably in the range of 35 to 70% in terms of the ratio of the hollow particle mass to the total solid mass of the entire intermediate layer. When the mass ratio of the hollow particles to the total solid mass of the entire intermediate layer is less than 30%, the heat insulating property and cushioning property of the intermediate layer are insufficient, and the sensitivity and image quality improvement effect may not be sufficiently obtained. On the other hand, if the mass ratio of the hollow particles exceeds 75%, the coating properties of the resulting intermediate layer paint may be lowered, resulting in insufficient coating strength, and the desired effect may not be obtained. .

  In order for the intermediate layer to exhibit desired performance such as heat insulation and cushioning, the thickness of the intermediate layer is preferably 20 to 90 μm, more preferably 25 to 85 μm. If the film thickness of the intermediate layer is less than 20 μm, the heat insulation and cushioning properties are insufficient, and the sensitivity and image quality improvement effect may be insufficient. On the other hand, if the film thickness exceeds 90 μm, the effects of heat insulation and cushioning are saturated, and not only higher performance can be obtained, but also it may be economically disadvantageous.

  The intermediate layer of the present invention contains hollow particles and an adhesive resin. The intermediate layer coating material of the present invention is preferably an aqueous coating material in consideration of the solvent resistance of the hollow particles. Accordingly, the adhesive resin can be either water-based or organic solvent-based, but is more preferably an aqueous resin. The adhesive resin used is not particularly limited. For example, hydrophilic polymer resins such as polyvinyl alcohol resins, cellulose resins and derivatives thereof, casein, and starch derivatives are film forming properties, heat resistance, and flexibility. Are preferably used. In addition, emulsions of various resins such as (meth) acrylic acid ester resins, styrene-butadiene copolymer resins, urethane resins, polyester resins, ethylene-vinyl acetate copolymer resins are used as low-viscosity and high-solids aqueous resins. The The adhesive resin used for the intermediate layer is preferably a combination of the hydrophilic polymer resin and an emulsion of various resins from the viewpoints of coating strength, adhesiveness, and coatability of the intermediate layer.

  In the intermediate layer, various additives, for example, an antistatic agent, an inorganic pigment, an organic pigment, a resin crosslinking agent, an antifoaming agent, a dispersing agent, a colored dye, a release agent, a lubricant, etc. Two or more kinds may be appropriately selected and used.

(Barrier layer)
In the present invention, if necessary, a barrier layer may be provided on the intermediate layer, and the receptor layer is provided on this barrier layer. In this barrier layer, the solvent of the coating material for the receiving layer is generally an organic solvent such as toluene and methyl ethyl ketone, and is effective as a barrier for preventing the hollow particles in the intermediate layer from swelling and dissolving due to penetration of the organic solvent. In addition, since the surface of the intermediate layer has irregularities due to the hollow particles of the intermediate layer, the receiving layer provided thereon may also have irregularities on the surface, and the resulting image has many white spots and uneven shading due to the irregularities. In some cases, problems arise in image uniformity and resolution. In order to improve this problem, it is effective to improve the image quality to provide a barrier layer containing a binder resin having flexibility and elasticity.

  As the resin used for the barrier layer, a resin having excellent film forming ability, preventing permeation of an organic solvent, and having elasticity and flexibility is used. Specifically, starch, modified starch, hydroxyethyl cellulose, methyl cellulose, carboxymethyl cellulose, gelatin, casein, gum arabic, fully saponified polyvinyl alcohol, partially saponified polyvinyl alcohol, carboxy modified polyvinyl alcohol, acetoacetyl group-modified polyvinyl alcohol, diester Isobutylene-maleic anhydride copolymer salt, styrene-maleic anhydride copolymer salt, styrene-acrylic acid copolymer salt, ethylene-acrylic acid copolymer salt, urea resin, urethane resin, melamine resin, amide resin, etc. The water-soluble polymer resin is used as an aqueous solution. Also, water-dispersible resins such as styrene-butadiene copolymer latex, acrylic ester resin latex, methacrylic ester copolymer latex, ethylene-vinyl acetate copolymer latex, polyester polyurethane ionomer, polyether polyurethane ionomer, etc. Can also be used. Among the above resins, water-soluble polymer resins are preferably used. Moreover, said resin may be used individually or may use 2 or more types together.

  In addition, in the intermediate layer and the barrier layer, in order to provide concealability and whiteness, and to improve the texture of the receiving sheet, as inorganic pigments, calcium carbonate, titanium dioxide, zinc oxide, aluminum hydroxide, barium sulfate, barium dioxide, White inorganic pigments such as silicon, aluminum oxide, talc, kaolin, diatomaceous earth, and satin white, fluorescent dyes, and the like may be included. As the inorganic pigment, a swellable inorganic layered compound is preferably used, and an excellent effect is obtained not only in preventing penetration of a coating solvent but also in preventing blurring of a thermal transfer dyed image. Specific examples of the swellable inorganic layered compound include graphite, phosphate derivative compounds (such as zirconium phosphate compounds), chalcogenides, hydrotalcite compounds, lithium aluminum composite hydroxides, clay minerals (for example, Synthetic mica, synthetic smectite, smectite group, vermiculite group, mica group, etc.).

The barrier layer of the present invention is preferably formed using an aqueous coating solution. In order to prevent the swelling and dissolution of hollow particles, the aqueous coating solution is a ketone solvent such as methyl ethyl ketone, an ester solvent such as ethyl acetate, a lower alcohol solvent such as methyl alcohol or ethyl alcohol, or a hydrocarbon solvent such as toluene or xylene. It is preferable not to contain an organic solvent such as a high boiling point and high polarity solvent such as a solvent, DMF or cellosolve. The solid content coating amount of the barrier layer is preferably in the range of 0.5 to 10 g / m ² , more preferably in the range of 1 to 8 g / m ² . Incidentally, when the barrier layer solid content coating amount is less than 0.5 g / m ² , the barrier layer may not completely cover the surface of the intermediate layer, and the organic solvent permeation preventing effect may be insufficient. On the other hand, when the coating amount of the barrier layer solid content exceeds 10 g / m ² , the coating effect is saturated and not only uneconomical, but also the heat insulation effect of the intermediate layer due to the excessive thickness of the barrier layer The cushioning property may not be sufficiently exhibited, and the image density may be lowered.

(Receptive layer)
In the receiving sheet of the present invention, a receiving layer is provided on the intermediate layer or via a barrier layer. The receiving layer itself may be a known dye thermal transfer receiving layer. As the resin for forming the receiving layer, a resin having a high affinity for the dye transferred from the ink ribbon and having a good dyeing property is used. Examples of such dye-dyeable resins include polyester resins, polycarbonate resins, polyvinyl chloride resins, vinyl chloride-vinyl acetate copolymer resins, polyvinyl acetal resins, polyvinyl butyral resins, polystyrene resins, polyacrylate resins, and cellulose. Examples thereof include cellulose derivative resins such as acetate butyrate, thermoplastic resins such as polyamide resin, and active energy ray curable resins. These resins preferably have a functional group reactive with the crosslinking agent used (for example, a functional group such as a hydroxyl group, an amino group, a carboxyl group, or an epoxy group).

  In addition, in order to prevent the receiving layer and the ink ribbon from fusing by heating with a thermal head during printing, one or more of a crosslinking agent, a release agent, a slipping agent, etc. are added to the receiving layer. It is preferable that it is mix | blended as an agent. Moreover, you may add 1 or more types, such as fluorescent dye, a plasticizer, antioxidant, a pigment, a filler, an ultraviolet absorber, antistatic agent, etc. in said receiving layer as needed. These additives may be mixed with the forming component of the receiving layer before coating, or may be coated on and / or under the receiving layer as a coating layer different from the receiving layer.

The solid coating amount of the receiving layer is preferably 1 to 12 g / m ² , more preferably 3 to 10 g / m ² . Incidentally, if the solid coating amount of the receiving layer is less than 1 g / m ² , the receiving layer may not completely cover the surface of the barrier layer, resulting in deterioration of the image quality or heating of the thermal head. There may be a fusing problem that the ink ribbon adheres. On the other hand, when the solid content coating amount exceeds 12 g / m ² , not only is the effect saturated and uneconomical, but also the coating film strength of the receiving layer is insufficient or the coating film thickness is excessive. Further, the heat insulating effect of the sheet-like support may not be sufficiently exhibited, and the image density may be lowered.

(Back layer)
In the receiving sheet of the present invention, a back layer may be provided on the back side of the sheet-like support (the side opposite to the side on which the receiving layer is provided). The back layer is mainly composed of a resin effective as an adhesive, and may contain a crosslinking agent, a conductive agent, an anti-fusing agent, an inorganic and / or organic pigment, and the like.

  For the back layer of the present invention, a back layer forming resin effective as an adhesive is used. This resin is effective in improving the adhesive strength between the back surface layer and the sheet-like support, print transportability of the receiving sheet, preventing scratches on the receiving layer surface, and preventing the dye from transferring to the back layer contacting the receiving layer surface. As such a resin, an acrylic resin, an epoxy resin, a polyester resin, a phenol resin, an alkyd resin, a urethane resin, a melamine resin, a polyvinyl acetal resin, and a reaction cured product of these resins can be used.

  In the back layer of the present invention, a cross-linking agent such as a polyisocyanate compound or an epoxy compound may be appropriately added to the back layer coating material in order to improve the adhesion between the sheet-like support and the back layer. As a compounding ratio, generally about 1-30 mass% is preferable with respect to the back layer total solid content.

  A conductive agent such as a conductive polymer or a conductive inorganic pigment may be added to the back layer of the present invention in order to improve print transportability and prevent static electricity. Examples of the conductive polymer include cationic, anionic and nonionic conductive polymer compounds. Examples of the cationic polymer compound include polyethyleneimine, acrylic polymers containing cationic monomers, and cation-modified acrylamide polymers. And cationic starch. Examples of the anionic polymer compound include polyacrylate, polystyrene sulfonate, and styrene-maleic acid copolymer. In general, the blending ratio of the conductive agent is preferably about 5 to 50% by mass with respect to the total solid content of the back surface layer.

  Examples of conductive inorganic pigments include compound semiconductor pigments such as oxides and / or sulfides, and inorganic pigments coated with the compound semiconductor pigments. Examples of the compound semiconductor include copper (I) oxide, zinc oxide, zinc sulfide, and silicon carbide. Examples of inorganic pigments coated with a compound semiconductor include titanium oxide and potassium titanate coated with semiconductor tin oxide, and acicular and spherical conductive inorganic pigments are commercially available.

  If necessary, an organic or inorganic filler can be blended in the back layer of the present invention as a friction coefficient adjusting agent. As the organic filler, nylon filler, cellulose filler, urea resin filler, styrene resin filler, acrylic resin filler, and the like can be used. As the inorganic filler, silica, barium sulfate, kaolin, clay, talc, heavy calcium carbonate, light calcium carbonate, titanium oxide, zinc oxide and the like can be used. For example, in the case of a nylon filler, the average particle size is preferably about 1 to 25 μm, and the blending amount is preferably about 2 to 30% by mass with respect to the total solid content of the back surface layer, although it depends on the particle size.

  The back layer may contain an anti-fusing agent such as a lubricant and a release agent as necessary. Examples of the anti-fusing agent include non-modified and modified silicone oils, silicone block copolymers, silicone compounds such as silicone rubber, phosphate ester compounds, fatty acid ester compounds, fluorine compounds, and the like. Conventionally known antifoaming agents, dispersants, colored pigments, fluorescent dyes, fluorescent pigments, ultraviolet absorbers and the like may be appropriately selected and used.

The solid content coating amount of the back layer is preferably in the range of 0.3 to 10 g / m ² . More preferably, it is 1-8 g / m < ² >. When the back layer solid content coating amount is less than 0.3 g / m ² , scratch resistance when the receiving sheet is rubbed is not sufficiently exhibited, coating defects are generated, and the surface electrical resistance value is May go up. On the other hand, if the solid content coating amount exceeds 10 g / m ² , the effect is saturated and uneconomical.

(Undercoat layer)
In the receiving sheet of the present invention, an undercoat layer mainly composed of a polymer resin may be provided between the support and the intermediate layer. With this undercoat layer, even when the intermediate layer coating liquid is applied onto the support, the intermediate layer can be formed in a desired thickness without the coating liquid penetrating into the support. . Examples of the polymer resin used for the undercoat layer include acrylic resins, polyurethane resins, polyester resins, polyolefin resins, and modified resins thereof.

  For example, when a paper base material is used as a support in the present invention, when an undercoat layer made of an aqueous coating solution is applied, the paper base material is wrinkled due to uneven water absorption on the paper base material surface. Swelling may occur, adversely affecting the texture and printability. Therefore, in such a case, it is preferable to use a coating solution in which a polymer resin is dissolved or dispersed in an organic solvent, not an aqueous coating solution. Usable organic solvents include common organic solvents such as toluene, methyl ethyl ketone, isopropyl alcohol, and ethyl acetate.

For the undercoat layer, titanium dioxide, calcium carbonate, barium sulfate, etc. are used to improve the coatability of the undercoat layer coating solution itself, improve the adhesion to the support and the intermediate layer, and improve the whiteness of the receiving sheet. The white inorganic pigment may be added. The solid coating amount of the undercoat layer is preferably in the range of 1 to ²⁰ g / m2. If the solid content coating amount is less than 1 g / m ² , the effect of the undercoat layer may not be obtained. If the solid content coating amount exceeds 20 g / m ² , the effect of the undercoat layer is saturated and uneconomical. In addition, the texture of the receiving sheet as paper may be lost.

The method for producing a receiving sheet of the present invention includes at least the following steps.
On at least one surface of the sheet-like support, (a) an intermediate layer coating solution containing hollow particles having an average particle diameter of 0.5 to 10 μm and a volume hollowness of 75 to 95% is applied and dried. After the intermediate layer is provided and / or (b) the image receiving layer is provided on the intermediate layer, (c) a smoothing process is performed through a nip portion of a pair of rolls including a heating roll and a press roll. Using the microtopograph on the surface of the receiving sheet, the printing smoothness (Rp value) measured after 10 msec of applied pressure 0.1 MPa and pressurization is adjusted to 1.5 μm or less.
Further, after the step (a) of providing the intermediate layer, it is preferable to further provide a barrier layer on the intermediate layer, and provide a receiving layer on the barrier layer. You may have the process of providing a back surface layer in the side in which the receiving layer of a sheet-like support body is not provided.

  In the present invention, the intermediate layer, the barrier layer, the receiving layer, the back layer, and the other coating layers are formed according to a conventional method, and each of them prepares a coating solution containing necessary components, and a bar coater, a gravure coater, a comma Using a known coater such as a coater, a blade coater, an air knife coater, a gate roll coater, a die coater, a curtain coater, a lip coater, and a slide bead coater, coating on a predetermined surface of a sheet-like support, After drying, it can be heated and cured as necessary.

  For example, when the intermediate layer is applied, a molding surface may be used, or a metal plate, a metal drum, a plastic film, or the like having good dimensional stability and a highly smooth surface may be used. Moreover, in order to make it easy to peel the intermediate layer from the molding surface, if necessary, a higher fatty acid type release agent such as calcium stearate and zinc stearate, a polyethylene type release agent such as polyethylene emulsion, and wax on the molding surface. In addition, a release agent such as silicone may be applied.

  In the method for producing a receiving sheet of the present invention, as a smoothing treatment step, for example, a smoothing process is performed by reducing irregularities on the surface of the receiving sheet through a receiving sheet between a pair of rolls composed of a heating roll and a press roll with a certain clearance. It is preferable to perform calendar processing. At this time, heat and pressure can be applied between the pair of rolls.

  In the smoothing treatment, the printing smoothness (Rp value) measured using a microtopograph on the surface of the finally obtained receiving sheet using an applied pressure of 0.1 MPa and 10 msec after starting pressurization can be 1.5 μm or less. The smoothing treatment may be performed on any of the sheet-like support surface, the intermediate layer surface, the barrier layer surface, the receiving layer surface, and the like. In particular, the surface of the intermediate layer and the surface of the receiving layer are preferably subjected to a smoothing treatment. Of course, the smoothing treatment can be performed on two or more surfaces.

  There are no particular limitations on the calender apparatus used for the smoothing process and various processing conditions such as the nip pressure, the number of nips, and the heating roll surface temperature. Examples of the calender apparatus include a super calender, soft calender, gloss A calendar device generally used in the paper industry such as a calendar, a machine calendar, and a clearance calender can be appropriately used.

  A preferable nip pressure condition for the smoothing treatment is, for example, 0.2 to 150 MPa, and more preferably 0.3 to 100 MPa. Further, the residence time of the receiving sheet at the nip is greatly affected by the hardness of the press roll, the linear pressure of the calendar, the processing speed, etc., but is preferably in the range of 5 to 500 milliseconds. As temperature conditions of a heating roll, the temperature range below the melting point of the binder of the coating layer which performs a smoothing process from room temperature is preferable, for example, 20-150 degreeC, More preferably, it is 30-120 degreeC. Moreover, as for the surface roughness of a heating roll, it is preferable that Ra value based on JISB0601 is 0.01-5 micrometers, More preferably, it is the range of 0.02-1 micrometer.

  As shown in the explanatory diagram of FIG. 1, the manufacturing method of the receiving sheet according to the present invention has a thickness in which the receiving sheet is brought into contact with a heating roll and heated immediately after the smoothing treatment step in a pressure-released state. A restoration processing step may be included. When the receiving sheet is smoothed by passing through a nip in a pressurized state formed between a pair of rolls consisting of a heating roll and a press roll, the smoothness is improved, but the inside of the receiving sheet, particularly The intermediate layer is compressed to reduce the thickness. When this receiving sheet is brought into contact with a heating roll in a pressure-released state immediately after passing through the nip portion, the intermediate layer expands and the thickness increases, so that the density of the entire intermediate layer decreases, and the printing density of the receiving sheet decreases. Can be increased.

  The temperature of the heating roll in the thickness restoration treatment step may be the same as the heating roll condition in the smoothing treatment, preferably 20 to 150 ° C, more preferably 30 to 120 ° C. The contact time between the receiving sheet and the heating roll is preferably 0.5 seconds or longer, more preferably 1 second or longer.

(Image forming method)
In sublimation thermal transfer printers currently on the market, sublimation dye is thermally transferred from the ink ribbon to the receiving layer of the receiving sheet, and when an image is formed, it is applied to the receiving sheet by the pressing force between the printer thermal head and the platen roll. The pressure is about 0.1 to 0.5 MPa.
The receiving sheet of the present invention is preferably subjected to a pressure treatment of 1.0 MPa or more on the receiving sheet surface during and / or after printing in order to improve the strength of the surface of the printed material. It is more preferable to perform a pressure treatment of ˜5 MPa.

Examples of the pressure treatment on the surface of the receiving sheet include the following methods (1) to (4).
(1) After printing under normal conditions, the nip roll pressure is adjusted, and a predetermined pressing process is performed on the receiving sheet.
(2) After printing under normal conditions, the presser pressure of the platen roll is adjusted to perform predetermined pressurization and paper passing processing on the receiving sheet.
(3) When the printing method is a three-time transfer process of yellow, magenta, and cyan, the presser pressure of the platen roll is adjusted during the final cyan transfer, and predetermined pressurization and transfer processes are performed on the receiving sheet. .
(4) When the printing method is a four-time transfer process of yellow, magenta, cyan, and transparent protective layer, the presser pressure of the platen roll is adjusted at the time of the last transparent protective layer transfer to apply a predetermined amount to the receiving sheet. Perform pressure and transfer processing.
Selection of the above method is appropriately performed in consideration of the cost of the apparatus, processing speed, ease of control, and the like.

  The present invention will be described in detail by the following examples, but the scope of the present invention is not limited thereto. In Examples, unless otherwise specified, “%” and “parts” represent “mass%” and “parts by mass” of solid content, except for those relating to solvents.

Example 1
"Formation of back layer"
As a sheet-like support, art paper (trade name: OK Kanto N, 174.4 g / m ² , manufactured by Oji Paper Co., Ltd.) having a thickness of 150 μm is used, and coating liquid 1 for the back layer having the following composition is applied on one side thereof. The back layer was formed by coating and drying so that the solid coating amount after drying was 3 g / m ² .
Back layer coating solution-1
Polyvinyl acetal resin (trade name: ESREC KX-1, manufactured by Sekisui Chemical Co., Ltd.) 40 parts polyacrylic acid ester resin (trade name: Jurimer AT613, manufactured by Nippon Pure Chemical) 20 parts nylon resin particles (trade name: MW330, manufactured by Shinto Fine) ) 10 parts zinc stearate (trade name: Z-7-30, manufactured by Chukyo Yushi) 10 parts cationic conductive resin (trade name: Chemistat 9800, manufactured by Sanyo Chemical) 20 parts water / isopropyl alcohol = 2/3 (mass) Ratio) 400 parts of liquid mixture

"Formation of an intermediate layer"
Next, the intermediate layer coating solution-1 having the following composition is applied on the surface opposite to the side on which the back surface layer of the sheet-like support is provided, and dried so that the film thickness after drying is 43 μm. Then, an intermediate layer was formed, and calendering (roll surface temperature 80 ° C., nip pressure 2.5 MPa) was performed for smoothing the surface.
Intermediate layer coating solution-1
Polyvinylidene chloride-based foamed hollow particles (volume hollow ratio 93%, average particle diameter 4 μm, maximum particle diameter 20 μm) 35 parts polyvinyl alcohol (trade name: PVA205, manufactured by Kuraray) 15 parts styrene-butadiene latex (trade name: PT1004, Made by Nippon Zeon) 50 parts water 200 parts

"Creating a receiving sheet"
Further, on the intermediate layer, a barrier layer coating solution-1 having the following composition was applied and dried so that the solid coating amount was 2 g / m ² , and a barrier layer was formed. The receiving layer coating solution-1 having the following composition was coated and dried so that the solid content coating amount was 5 g / m ² , and then cured at 50 ° C. for 48 hours to form a receiving layer, and a receiving sheet It was created.
Coating liquid for barrier layer-1
Polyvinyl alcohol (trade name: PVA420, manufactured by Kuraray) 100 parts Water 1000 parts
Receiving layer coating solution-1
Polyester resin (trade name: Byron 200, manufactured by Toyobo) 100 parts silicone oil (trade name: KF393, manufactured by Shin-Etsu Chemical Co., Ltd.) 3 parts polyisocyanate (trade name: Takenate D-140N, manufactured by Takeda Pharmaceutical Co., Ltd.) 5 parts Toluene / Methyl ethyl ketone = 1/1 (mass ratio) mixture 400 parts "Image formation processing"
Using a commercially available thermal transfer video printer (trade name: UP-DR100, manufactured by Sony Corporation), an ink layer containing sublimation dyes of yellow, magenta, and cyan with a binder on a 6 μm thick polyester film. Each ink layer of the provided ink ribbon is brought into contact with the receiving sheet in sequence, and heating is controlled stepwise by a thermal head, whereby a predetermined image is thermally transferred to the receiving sheet, so that a single color and a halftone of each color are obtained. Overlaid images were printed. The obtained image sheet was passed between a metal roll pressurized to 1.5 MPa (contact with the marking screen, diameter 30 mm) and a rubber roll (contact with the back surface, diameter 30 mm).

Example 2
In the formation of the intermediate layer, Example 1 was used except that the intermediate layer was formed by using an intermediate layer coating liquid-2 having the following composition and coating and drying so that the film thickness after drying was 25 μm. Similarly, a receiving sheet was prepared, and the receiving sheet after printing was subjected to pressure treatment.
Intermediate layer coating liquid-2
Copolymer-based foamed hollow particles mainly composed of acrylonitrile and acrylate ester (volume hollow ratio 79%, average particle diameter 3.6 μm, maximum particle diameter 19 μm) 35 parts polyvinyl alcohol (trade name: PVA205, manufactured by Kuraray Co., Ltd.) 15 Part styrene-butadiene latex (trade name: PT1004, manufactured by Zeon Corporation) 50 parts water 200 parts

Example 3
In the formation of the intermediate layer, Example 1 was used except that the intermediate layer was formed by using an intermediate layer coating liquid-3 having the following composition and coating and drying so that the film thickness after drying was 40 μm. Similarly, a receiving sheet was prepared, and the receiving sheet after printing was subjected to pressure treatment.
Intermediate layer coating solution-3
Copolymer based foamed hollow particles mainly composed of acrylonitrile and acrylate ester (volume hollow ratio 79%, average particle diameter 3.6 μm, maximum particle diameter 19 μm) 55 parts polyvinyl alcohol (trade name: PVA205, manufactured by Kuraray Co., Ltd.) 15 Part styrene-butadiene latex (trade name: PT1004, manufactured by Nippon Zeon) 30 parts water 200 parts

Example 4
In the formation of the intermediate layer, Example 1 was used except that the intermediate layer was formed by coating and drying the intermediate layer coating liquid-4 having the following composition so that the film thickness after drying was 50 μm. Similarly, a receiving sheet was prepared, and the receiving sheet after printing was subjected to pressure treatment.
Intermediate layer coating solution-4
Copolymer based foamed hollow particles mainly composed of acrylonitrile and acrylic ester (volume hollow ratio 80%, average particle diameter 8.0 μm, maximum particle diameter 25 μm) 35 parts polyvinyl alcohol (trade name: PVA205, manufactured by Kuraray Co., Ltd.) 15 Part styrene-butadiene latex (trade name: PT1004, manufactured by Zeon Corporation) 50 parts water 200 parts

Example 5
The intermediate layer was formed in the same manner as in Example 1 except that an intermediate layer coating solution-5 having the following composition was used, and the intermediate layer was formed by coating and drying so that the film thickness after drying was 65 μm. Then, a receiving sheet was prepared, and the receiving sheet after printing was subjected to pressure treatment.
Intermediate layer coating solution-5
Copolymer-based foamed hollow particles mainly composed of acrylonitrile and acrylate ester (volume hollow ratio 88%, average particle diameter 4.4 μm, maximum particle diameter 20 μm) 55 parts polyvinyl alcohol (trade name: PVA205, manufactured by Kuraray Co., Ltd.) 15 Part styrene-butadiene latex (trade name: PT1004, manufactured by Nippon Zeon) 30 parts water 200 parts

Example 6
The intermediate layer was formed in the same manner as in Example 1 except that an intermediate layer coating solution-6 having the following composition was used, and the intermediate layer was formed by coating and drying so that the film thickness after drying was 33 μm. Then, a receiving sheet was prepared, and the receiving sheet after printing was subjected to pressure treatment.
Intermediate layer coating solution-6
Copolymer-based preformed hollow particles mainly composed of acrylonitrile and acrylate ester (volume hollow ratio 77%, average particle diameter 5.2 μm, maximum particle diameter 24 μm) 45 parts polyvinyl alcohol (trade name: PVA205, manufactured by Kuraray Co., Ltd.) 15 Part styrene-butadiene latex (trade name: PT1004, manufactured by Zeon Corporation) 40 parts water 200 parts

Example 7
Using a receiving sheet prepared in the same manner as in Example 1, printing was performed by the following method, and then pressure treatment was performed during the formation of the protective layer.
"Image formation processing"
Using a commercially available thermal transfer video printer (thermal head / platen roll pressure 0.8 MPa), an ink layer containing sublimation dyes of yellow, magenta, and cyan with a binder is provided on a 6 μm thick polyester film. Each ink layer of the ink ribbon is brought into contact with the receiving sheet in sequence, and a predetermined image is thermally transferred to the receiving sheet by applying a stepwise controlled heating with a thermal head, so that a single color and halftone of each color are transferred. Images were printed.
After adjusting the pressure between the thermal head and the platen roll to 4.5 MPa, the obtained image sheet is brought into contact with the receiving sheet with a sheet provided with a transparent resin layer on a polyester film having a thickness of 6 μm. The protective layer was thermally transferred to the receiving sheet by heating at.

Example 8
Using the receiving sheet prepared in the same manner as in Example 1, when the protective layer was formed after printing, the protective layer was formed with the pressure between the thermal head and the platen roll as it was (0.8 MPa). The image forming process was carried out in the same manner as in Example 7 except that the film was thermally transferred.

Example 9
"Formation of back layer"
A 150 μm thick art paper (trade name: OK Kanto N, 174.4 g / m ² , made by Oji Paper Co., Ltd.) was used as the sheet-like support, and the back layer coating solution-1 (Example 1) was used on one side thereof. Was prepared so that the solid content coating amount was 3 g / m ² and dried to form a back layer.
"Formation of an intermediate layer"
Next, the intermediate layer coating solution-2 (prepared in Example 2) is applied onto the surface of the sheet-like support opposite to the side on which the back surface layer is provided so that the film thickness after drying is 53 μm. The intermediate layer was formed by drying.
"Creating a receiving sheet"
Further, a barrier layer coating solution-1 (prepared in Example 1) was applied on the intermediate layer so that the solid coating amount was 2 g / m ² and dried to form a barrier layer. On the barrier layer, the coating solution for receiving layer-1 (prepared in Example 1) was coated and dried so that the solid content coating amount was 5 g / m ² , and then cured at 50 ° C. for 48 hours. A receiving layer was formed. Further, a calendar process (roll surface temperature 78 ° C., nip pressure 2.5 MPa) was performed for smoothing the surface to prepare a receiving sheet.
"Image formation processing"
Using the obtained receiving sheet, after image printing was carried out in the same manner as in Example 7, pressure was applied during the formation of the protective layer to perform image formation processing.

Example 10
In Example 9, an image forming process was performed in the same manner as in Example 9 except that “receiving sheet creation” was changed as follows to form a receiving sheet.
"Creating a receiving sheet"
The coating amount for barrier layer-1 (prepared in Example 1) applied to the intermediate layer obtained in “Formation of the back layer” and “Formation of the intermediate layer” in Example 9 was a solid coating amount. A barrier layer is formed by coating and drying so as to be ² g / m ^{2. On} this barrier layer, a coating solution for receiving layer-1 (prepared in Example 1) is applied at a solid content of 5 g / m ^2. It was coated and dried to m ² and then cured at 50 ° C. for 48 hours to form a receiving layer. Further, calendering (roll surface temperature 78 ° C., nip pressure 2.5 MPa) is performed to smooth the surface of the receiving layer, and immediately after releasing the pressure, the receiving layer surface is brought into contact with a roll having a surface temperature of 78 ° C. for 2 seconds. A thickness restoration process was performed to obtain a receiving sheet.
"Image formation processing"
Using the obtained receiving sheet, after image printing was carried out in the same manner as in Example 7, pressure was applied during the formation of the protective layer to perform image formation processing.

Example 11
"Formation of back layer"
A 150 μm thick art paper (trade name: OK Kanto N, 174.4 g / m ² , made by Oji Paper Co., Ltd.) was used as the sheet-like support, and the back layer coating solution-1 (Example 1) was used on one side thereof. The back layer was formed by coating and drying so that the solid coating amount after drying was 3 g / m ² .
"Formation of an intermediate layer"
Next, the intermediate layer coating solution-5 (prepared in Example 5) is applied on the surface of the sheet-like support opposite to the side provided with the back layer so that the film thickness after drying becomes 65 μm. The intermediate layer was formed by drying.
"Creating a receiving sheet"
Further, a barrier layer coating solution-1 (prepared in Example 1) was applied on the intermediate layer so that the solid coating amount was 2 g / m ² and dried to form a barrier layer. On the barrier layer, the coating solution for receiving layer-1 (prepared in Example 1) was coated and dried so that the solid content coating amount was 5 g / m ² , and then cured at 50 ° C. for 48 hours. A receiving layer was formed. Further, calendering (roll surface temperature 78 ° C., nip pressure 2.5 MPa) is performed for smoothing the surface of the receiving layer, and immediately after releasing the pressure, the receiving layer surface is brought into contact with a roll having a surface temperature of 78 ° C. for 2 seconds. A thickness restoration process was performed to obtain a receiving sheet.
"Image formation processing"
Using the obtained receiving sheet, after image printing was performed in the same manner as in Example 7, pressure was applied during the formation of the protective layer to perform image formation processing.

Comparative Example 1
In the formation of the intermediate layer, Example 1 was used except that the intermediate layer was formed by coating and drying the intermediate layer coating solution -7 having the following composition so that the film thickness after drying was 35 μm. Similarly, a receiving sheet was prepared, and the receiving sheet after printing was subjected to pressure treatment.
Intermediate layer coating solution -7
Copolymer-based pre-expanded hollow particles mainly composed of acrylonitrile and acrylate (volume hollow ratio 97%, average particle diameter 4.4 μm, maximum particle diameter 20 μm) 35 parts polyvinyl alcohol (trade name: PVA205, manufactured by Kuraray Co., Ltd.) 15 Part styrene-butadiene latex (trade name: PT1004, manufactured by Zeon Corporation) 50 parts water 200 parts

Comparative Example 2
In the formation of the intermediate layer, Example 1 was used except that the intermediate layer was formed by using an intermediate layer coating liquid-8 having the following composition so that the thickness after drying was 20 μm. Similarly, a receiving sheet was prepared, and the receiving sheet after printing was subjected to pressure treatment.
Intermediate layer coating solution-8
Polyvinyl alcohol (trade name: PVA205, manufactured by Kuraray) 15 parts Styrene-butadiene latex (trade name: PT1004, manufactured by Nippon Zeon) 85 parts Water 200 parts

Comparative Example 3
In the formation of the intermediate layer, a receiving sheet was prepared in the same manner as in Example 1 except that the intermediate layer coating solution-9 having the following composition was used, and the receiving sheet after printing was subjected to pressure treatment.
Intermediate layer coating solution-9
Copolymer based foamed hollow particles mainly composed of acrylonitrile and acrylic ester (volume hollow ratio 77%, average particle diameter 15.0 μm, maximum particle diameter 35 μm) 35 parts polyvinyl alcohol (trade name: PVA205, manufactured by Kuraray Co., Ltd.) 15 Part styrene-butadiene latex (trade name: PT1004, manufactured by Zeon Corporation) 50 parts water 200 parts

Comparative Example 4
In the formation of the intermediate layer, Example 1 was used except that the intermediate layer was formed by coating and drying the intermediate layer coating liquid-10 having the following composition so that the film thickness after drying was 60 μm. Similarly, a receiving sheet was prepared, and the receiving sheet after printing was subjected to pressure treatment.
Intermediate layer coating solution-10
Copolymer-based pre-expanded hollow particles mainly composed of acrylonitrile and acrylic ester (volume hollow ratio 65%, average particle diameter 5.2 μm, maximum particle diameter 24 μm) 30 parts polyvinyl alcohol (trade name: PVA205, manufactured by Kuraray Co., Ltd.) 15 Part styrene-butadiene latex (trade name: PT1004, manufactured by Nippon Zeon) 55 parts water 200 parts

Comparative Example 5
A receiving sheet was prepared in the same manner as in Example 4, and the receiving sheet after printing was subjected to pressure treatment.
However, calendering for surface smoothing was not performed in the formation of the intermediate layer.

Evaluation The receiving sheets obtained in each of the above examples and comparative examples were evaluated by the following methods, and the results obtained are shown in Table 1.

"Print smoothness"
Using a printing smoothness tester (Microtopograph, manufactured by Toyo Seiki Seisakusho), the printing smoothness (Rp value) 10 msec after the start of pressurization at an applied pressure of 0.1 MPa was measured.

"Compressive modulus"
The compression modulus of the receiving sheet was measured according to JIS K 7220 (Method for testing compression of hard foam plastic). However, the height (thickness) of the test piece was the thickness (about 200 μm) of the test receiving sheet. The compression speed was 20 μm / min.

"Print quality" (print density, image uniformity)
Using the printed matter obtained in each of the above Examples and Comparative Examples, a Macbeth reflection densitometer (trade name: RD-914, manufactured by Kollmorgen) is used for the recorded image for each applied energy transferred onto the receiving sheet. Then, the reflection density was measured. The density of the high gradation portion corresponding to the 15th step from the lowest applied energy is displayed in Table 1 as the print density.
Further, as an evaluation of the uniformity of the recorded image, visual observation was performed for the presence or absence of uneven density and white spots in a gradation portion corresponding to an optical density (black) of 0.3.
Excellent evaluation results were indicated by ◎, good results by ◯, dark unevenness and white spotting slightly recognized by Δ, and uneven density and white defect defects marked by x.

"Abrasion evaluation"
The surface of the printed matter obtained in each of the above Examples and Comparative Examples was visually evaluated for the ease of scratching scars by nails. A sample having excellent evaluation results was indicated by も の, a good one by ○, a slight scar by Δ, and a marked scar by ×.

表１から明らかなように、本発明の実施例で得られた受容シートは、印画濃度、画像均一性等において実用に適したものであった。また、実施例８においては、印画物の加圧処理がされていないため、実用には問題がない程度であるが、擦過性において傷跡が若干認められた。
一方、比較例１〜５で得られた受容シートは、印画濃度、或は画像均一性が不十分で実用に適さないものであった。

As apparent from Table 1, the receiving sheets obtained in the examples of the present invention were suitable for practical use in terms of printing density, image uniformity, and the like. Moreover, in Example 8, since the pressurization treatment of the printed matter was not performed, there was no problem in practical use, but some scratches were recognized in the scratch property.
On the other hand, the receiving sheets obtained in Comparative Examples 1 to 5 were not suitable for practical use because of insufficient printing density or image uniformity.

  The receiving sheet of the present invention has an intermediate layer containing hollow particles, and by reducing the printing smoothness to a certain value or less, uneven density and white spots are improved, and the receiving sheet for high sensitivity and high image quality recording. It is suitable for. Further, the print processing method of the present invention can improve the occurrence of scratches and scratches on the print surface, and can be applied to image formation by a dye thermal transfer printer.

Schematic which shows the smoothing process of a receiving sheet of this invention, and a thickness restoration process process.

Claims (2)

In the method for producing a thermal transfer receiving sheet in which an intermediate layer containing hollow particles and an image receiving layer are sequentially formed on at least one surface of a sheet-like support, the average particle diameter is 0.5 to at least on one surface of the sheet-like support. After applying the intermediate layer coating liquid containing hollow particles having a volumetric hollowness ratio of 75 to 95% at 10 μm and drying to provide the intermediate layer, and / or on the intermediate layer, the image After providing the receiving layer, a smoothing process is performed through the nip portion of a pair of rolls consisting of a heating roll and a press roll, and an applied pressure of 0.1 MPa is started using a microtopograph on the surface of the thermal transfer receiving sheet. The print smoothness (Rp value) measured after 10 msec is 1.5 μm or less, and after the smoothing treatment step, the surface of the thermal transfer receiving sheet is further released under pressure. A method for producing a thermal transfer receiving sheet, comprising a step of recovering the thickness of the heat transfer sheet in contact with a heating roll. In a thermal transfer receiving sheet in which an intermediate layer containing hollow particles and an image receiving layer are sequentially formed on at least one surface of a sheet-like support, the hollow particles have an average particle diameter of 0.5 to 10 μm and a volumetric hollow ratio of 75. Further, the printing smoothness (Rp value) measured by using a microtopograph on the surface of the thermal transfer receiving sheet with an applied pressure of 0.1 MPa and 10 msec after the start of pressurization is 1.5 μm or less. An image forming method, wherein the thermal transfer receiving sheet is subjected to a pressure treatment of 1.0 MPa or more on the surface of the thermal transfer receiving sheet during printing and / or after printing with a dye thermal transfer printer.

Images